MultiIndexImplem.H

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#ifdef CH_LANG_CC
/*
 *      _______              __
 *     / ___/ /  ___  __ _  / /  ___
 *    / /__/ _ \/ _ \/  V \/ _ \/ _ \
 *    \___/_//_/\___/_/_/_/_.__/\___/
 *    Please refer to Copyright.txt, in Chombo's root directory.
 */
#endif

#ifndef _MULTIINDEXIMPLEM_H_
#define _MULTIINDEXIMPLEM_H_

#include "NamespaceHeader.H"

// Generate and return a vector of all multi-indices whose magnitude (the sum
// of their entries) equals "a_magnitude"
template <int dim> void generateMultiIndices(Vector<IndexTM<int,dim> > & a_indices,
                                             const int                 & a_magnitude)
{
  if (a_magnitude >= 0)
  {
    IndexTM<int,dim> monomial;

    for (int idir = 0; idir < dim; ++ idir)
    {
      monomial[idir] = 0;
    }

    while (true)
    {
      for (int j = 1; j < dim-1; ++j)
      {
        int t = a_magnitude;
        for (int k = j+1; k < dim; ++k)
        {
          t -= monomial[k];
        }

        if (monomial[j] > t)
        {
          monomial[j+1] += 1;
          monomial[j] = 0;
        }
        else
        {
          break;
        }
      }

      if (monomial[dim-1] > a_magnitude)
      {
        break;
      }

      monomial[0] = a_magnitude;

      for (int j = 1; j < dim; ++j)
      {
        monomial[0] -= monomial[j];
      }

      a_indices.push_back(monomial);

      monomial[1] += 1;
    }
  }
}

#include "NamespaceFooter.H"

#endif

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